status thread overwrites checkpoint information when REDIS_CHECKPOINT is enabled

[ikavalio]

Hi,

I've been testing some setups with REDIS_CHECKPOINT=true and noticed that my keys in redis contain txid_current but not checkpoint info most of the time. Sometimes the situation reverts and I only have checkpoint there.

After checking some code my theory is that status thread overwrites the complete document at regular interval in

pgsync/pgsync/sync.py

Line 2032 in 33eae21

self.redis.set_meta({"txid_current": self.txid_current})

As set_meta just runs redis SET command:

pgsync/pgsync/redisqueue.py

Lines 114 to 116 in 33eae21

	def set_meta(self, value: t.Any) -> None:
	"""Store an arbitrary JSON-serialisable value in a dedicated key."""
	self.__db.set(self._meta_key, json.dumps(value))

Checkpointer's setter does the same:

pgsync/pgsync/sync.py

Line 1614 in 33eae21

self.redis.set_meta({"checkpoint": value})

This is not a problem when REDIS_CHECKPOINT is disabled as far as I can tell, because both commands operate on 2 different files.

If the above is correct, I believe the code either needs to use 2 different redis keys, or use HSET / HGET for field level updates to prevent interference